A prospective study of all resuscitated out-of-hospital sudden death victims occurring in three communities in Michigan and Ohio will be continued for an additional three years. Using a registry of all emergency cardiac runs, all patients who are resuscitated and successfully leave the acute care medical facility will be identified and their entry event classified. These patients will be followed serially and new clinical events, clinical status and serial ambulatory ECG recordings will be obtained. Our objected is to develop a multi-variate prognostic index in this patient population based upon the entry event and serial changes in the clinical status and ambulatory ECG. We will also study the logistic problem of providing emergency medical care in three separate communities and evaluate the effect of by-standard CPR on resuscitation rates.